Field of the Invention
The invention relates to a method for producing a frame around a video image, and to a device for producing a frame around a matrix-like video image, which is in particular suitable for implementing the method.
There are various applications, in particular in television technology, in which a number of images are displayed simultaneously on a screen. Systems in which a smaller picture is inserted into a main picture are known under the designation picture-in-picture systems. In this case, the main picture and inserted picture are usually transmitted on different channels or originate from different video sources.
In order to emphasize the inserted image visually from the main image, the inserted image is provided with a frame. This frame is, for example, a number of pixels wide and runs around the edge of the inserted image.
The insertion of smaller images is also used on the transmitter side at the transmitting station or broadcasting studio. For example, interview partners who are located outside the broadcasting studio are often displayed in their own window within the picture recorded in the studio with the interviewer. Here, the transition from the window to the actual image is generally not carried out seamlessly. A border, which is most often black, ensures that the window stands out from the actual picture.
Both in the case of the inserted images and in the case of the windows described, the desired high degree of distinction, which is to be achieved by the frame, is not always accomplished. In particular in the case of very dark main images or in the case of very small or very large inserted images or windows, it is difficult for the observer to distinguish the main picture immediately and easily from the inserted picture or the window.